document.write( "Question 1081102: Three years ago, my age was a prime number.\r
\n" ); document.write( "\n" ); document.write( "• This year, my age is a multiple of 4.\r
\n" ); document.write( "\n" ); document.write( "I have a brother whose age twenty years ago was
\n" ); document.write( " half my current age. \r
\n" ); document.write( "\n" ); document.write( "• The sum of the digits of my age is equal to one\r
\n" ); document.write( "\n" ); document.write( "more than the product of the digits.\r
\n" ); document.write( "\n" ); document.write( "What is my age?\r
\n" ); document.write( "\n" ); document.write( "What is my brother’s age? \n" ); document.write( "

Algebra.Com's Answer #695210 by Edwin McCravy(20056) $\"\"$ $\"About$

You can put this solution on YOUR website!
• The sum of the digits of my age is equal to one
\n" ); document.write( "more than the product of the digits.
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document.write( "t = the tens digit of my age\r\n" );
document.write( "u = the ones or units digit of my age\r\n" );
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document.write( "t+u = tu+1\r\n" );
document.write( "t-tu = 1-u\r\n" );
document.write( "t(1-u)=1-u\r\n" );
document.write( "t=(1-u)/(1-u)\r\n" );
document.write( "t=1\r\n" );
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document.write( "So the tens digit is 1.  \r\n" );
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\n" ); document.write( "• This year, my age is a multiple of 4.
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document.write( "So my age is either 12 or 16, since those are the only\r\n" );
document.write( "two-digit multiples of 4 with tens digit 1.\r\n" );
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\n" ); document.write( "• Three years ago, my age was a prime number.
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document.write( "I can't be 12, for if I were, three years ago I would have been 9,\r\n" );
document.write( "but 9 is not a prime number.  So I must be 16, for 3 years ago I\r\n" );
document.write( "was 13, which is a prime number.\r\n" );
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document.write( "So my age is 16.\r\n" );
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\n" ); document.write( "• I have a brother whose age twenty years ago was
\n" ); document.write( " half my current age.
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document.write( "Half my age is 8, so for my brother to have been 8 years old 20 \r\n" );
document.write( "years ago, he must now be 8+20 or 28.\r\n" );
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document.write( "Edwin

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